Preheat oven to 375°F. Line a baking sheet with parchment paper. Set aside.
In a medium bowl, combine the flour, baking soda, and salt. Set aside.
1½ cups all-purpose flour, ½ teaspoon baking soda, ¼ teaspoon kosher salt
Using a hand mixer, gradually beat the butter and sugar together until soft. Add in the egg and beat until fluffy. Add in the milk, lemon juice, and lemon rind, until the batter is smooth.
¼ cup unsalted butter, ½ cup granulated sugar, 1 large egg, ¼ cup milk, 1 tablespoon lemon juice, 1 teaspoon grated lemon zest
Slowly add in the flour, scraping the sides of the bowl with a spatula. Stir in the poppy seeds until they are evenly distributed into the dough.
1 tablespoon poppy seeds
Scoop or spoon drops of the dough onto the prepared baking sheet. Place the cookie sheet in the center of the oven on the middle rack.
Bake for 8-10 minutes, until they become firm. Remove from the oven and allow to cool before glazing or frosting.